Display apparatus, manufacturing method of display apparatus, and electronic device

ABSTRACT

A display apparatus including: a display region provided with a plurality of pixel portions; wires installed to the respective pixel portions within the display region from an outside of the display region for transmitting a signal to drive the respective pixel portions; connection pads provided on the outside of the display region and serving as input portions to provide the wires with a signal while electrically conducting with the wires; switch elements provided on the outside of the display region in a middle of the wires; and a light shielding covering portion shielding the switch elements from light and formed to cover the connection pads while electrically conducting with the connection pads.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.15/923,540 filed Mar. 16, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/420,365 filed Jan. 31, 2017, now U.S. Pat. No.9,954,046 issued Apr. 24, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/244,904 filed Aug. 23, 2016, now U.S. Pat. No.9,608,051 issued Mar. 28, 2017, which is a continuation of U.S. patentapplication Ser. No. 13/965,687 filed Aug. 13, 2013, now U.S. Pat. No.9,461,200 issued Oct. 4, 2016, which is a continuation of U.S. patentapplication Ser. No. 12/699,470 filed Feb. 3, 2010, now U.S. Pat. No.8,513,879 issued Aug. 20, 2013, the entireties of all of which areincorporated herein by reference to the extent permitted by law. Thepresent application claims the benefit of priority to Japanese PatentApplication No. JP 2009-028050 filed on Feb. 10, 2009 in the JapanPatent Office, the entirety of which is incorporated by reference hereinto the extent permitted by law.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a display apparatus, a manufacturingmethod of a display apparatus, and an electronic device, and moreparticularly, to a display apparatus, a manufacturing method of adisplay apparatus, and an electronic device each of which is configurednot to give adverse influences of processing in the fabrication sequenceto the electrode surfaces of pixels.

2. Description of the Related Art

An organic EL (Electro Luminescence) panel displays a video by supplyinga current to respective pixels each having a vapor deposited organicelectroluminescence layer or the like from the side or top or bottom ofthe panel by way of metal wires as is described, for example, inJP-A-2008-257086. When an organic EL panel becomes larger, necessaryluminance of pixels increases and so does a current to be supplied.Also, because one wire becomes longer, wiring resistance becomes higher,which makes a voltage drop from the current supply end larger.

This voltage drop raises problems, such as the occurrence of non-uniformluminance and an increase of power consumption. Accordingly, a lowresistance material is used for the current supply metal layer with theaim at suppressing a voltage drop. Examples of a low resistance metalinclude but not limited to aluminum (Al), copper (Cu), gold (Au), andsilver (Ag). Of these candidates, Cu has a problem that it is quitedifficult to form a wire from Cu whereas Au and Ag have a problem thatthey are expensive. In view of the foregoing, Al is often used as metalfor low resistance wires.

Al can be processed by either wet etching or dry etching and isinexpensive. In a case where a single-layer Al wire is used, however,there is a concern about the generation of defects, such as hillock andspike.

The term, “hillock”, referred to herein means a semispherical protrusiongenerated on the wire surface due to heat history in the fabricationprocess. The term, “spike”, referred to herein means a phenomenon thatAl enters into silicon (Si) when Al is subjected to heat treatment whilein contact with Si.

As a countermeasure against these defects, there is a laminatedstructure to sandwich an Al wire between heat-resistant high meltingpoint metal. As a consequence, a metal layer aimed at anti-hillock andanti-spike appears on the surface of the top metal layer when Al is usedas a current supply metal layer.

A current flown through the current supply metal layer is injected intoan organic electroluminescence layer by way of electrodes of pixels. Itis therefore necessary for the electrodes of pixels to have acharacteristic that they are capable of injecting a current into theorganic electroluminescence layer. Normally, ITO (Indium Tin Oxide)having a high work function is used as a hole injecting electrode. As aconsequence, metal with a high capability of injecting holes into theorganic electroluminescence layer appears on the surface of a metallayer used as the electrodes of pixels.

SUMMARY OF THE INVENTION

An insulating film (opening defining insulating film) defining openingsof pixels is formed by the steps of applying photosensitive resinfollowed by exposure and peeling (development). When the openingdefining insulating film is peeled, pad portions for connecting anodeelectrodes and external wires (for example, flexible cables) are soakedin a peeling liquid at the same time. A battery corrosion reaction thustakes place and the surface nature of the anode electrodes isdeteriorated. Deterioration of the surface nature of the anodeelectrodes lowers the reflectance, which in turn lowers the luminance ofpixels.

Thus, it is desirable to provide a technique of preventing adverseinfluences of processing in the fabrication sequence from being given toelectrodes of pixels.

According to an embodiment of the present invention, there is provided adisplay apparatus including a display region provided with a pluralityof pixel portions, wires installed to the respective pixel portionswithin the display region from an outside of the display region andtransmitting a signal to drive the respective pixel portions, connectionpads provided on the outside of the display region and serving as inputportions that provide the wires with a signal while electricallyconducting with the wires, switch elements provided on the outside ofthe display region in a middle of the wires, and a light shieldingcovering portion shielding the switch elements from light and formed tocover the connection pads while electrically conducting with theconnection pads.

According to another embodiment of the present invention, there isprovided an electronic device having a main body casing provided withthe display apparatus configured as above.

According to the embodiments of the present invention, the lightshielding covering portion that shields the switch elements from lightis provided to cover the connection pads while electrically conductingwith the connection pads that electrically conduct with the wires. It istherefore possible to protect the surfaces of the connection pads withthe light shielding covering portion.

In a case where the pixel portion includes an organicelectroluminescence layer interposed between the anode electrode and thecathode electrode, by making the light shielding covering portion out ofthe same material as the anode electrode, it becomes possible to preventthe battery effect from being generated in the developing step carriedout while the anode electrode is in an exposed state.

According to still another embodiment of the present invention, there isprovided a manufacturing method of a display apparatus including thesteps of forming transistors for each pixel on a substrate, covering thetransistors with a first insulating film and planarizing a surface ofthe first insulating film, forming a second insulating film definingopenings of respective pixels between every two adjacent pixels on thefirst insulating film, forming anode electrodes in the openings of therespective pixels defined by the second insulating film, forming anorganic electroluminescence layer on the anode electrodes, and forming acathode electrode on the electroluminescence layer.

According to this embodiment of the present invention, the secondinsulating film that defines openings of the respective pixels is formedfirst and thence the anode electrodes are formed in the openings. Itthus becomes possible to prevent the influences in the step of formingthe second insulating film from being given to the anode electrodes.

According to the embodiments of the present invention, it becomespossible to prevent the adverse influences of the processing in thefabrication sequence from being given to the electrodes of pixels, whichcan in turn prevent deterioration of the display performance of thepixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view used to describe the planar configuration of a displayapparatus according to an embodiment of the present invention;

FIG. 2 is a view used to describe the circuit configuration of a majorportion of the display apparatus according to the embodiment of thepresent invention;

FIG. 3 is a pattern layout view used to describe an example of theconfiguration of a protection circuit;

FIG. 4 is a pattern layout view used to describe an example of theconfiguration of a test switch circuit;

FIG. 5 is a pattern layout view used to describe a light shieldingcovering portion in a protection circuit portion of the displayapparatus according to the embodiment of the present invention;

FIG. 6 is a pattern layout view used to describe a light shieldingcovering portion in a test switch circuit portion of the displayapparatus according to the embodiment of the present invention;

FIG. 7 is a cross section taken on line A-A′ of FIG. 6;

FIG. 8 is a cross section taken on line B-B′ of FIG. 6;

FIG. 9 is a view used to describe the planar configuration of the lightshielding covering portion;

FIG. 10 is a plan view used to describe another example of the lightshielding covering portion;

FIG. 11 is a first schematic cross section used to sequentially describethe manufacturing method of the display apparatus according to theembodiment of the present invention;

FIG. 12 is a second schematic cross section used to sequentiallydescribe the manufacturing method of the display apparatus according tothe embodiment of the present invention;

FIG. 13 is a third schematic cross section used to sequentially describethe manufacturing method of the display apparatus according to theembodiment of the present invention;

FIG. 14 is a fourth schematic cross section used to sequentiallydescribe the manufacturing method of the display apparatus according tothe embodiment of the present invention;

FIG. 15 is a first schematic cross section used to sequentially describeanother example of the manufacturing method of the display apparatusaccording to the embodiment of the present invention;

FIG. 16 is a second schematic cross section used to sequentiallydescribe another example of the manufacturing method of the displayapparatus according to the embodiment of the present invention;

FIG. 17 is a third schematic cross section used to sequentially describeanother example of the manufacturing method of the display apparatusaccording to the embodiment of the present invention;

FIG. 18 is a schematic view showing an example the display apparatus ofa flat modular shape;

FIG. 19 is a perspective view showing a TV set to which the presentinvention is applied;

FIG. 20A and FIG. 20B are perspective views showing a digital camera towhich the present invention is applied;

FIG. 21 is a perspective view showing a notebook personal computer towhich the present invention is applied;

FIG. 22 is a perspective view showing a video camera to which thepresent invention is applied; and

FIG. 23A through FIG. 23G are views showing a mobile terminal device,for example, a mobile phone, to which the present invention is applied.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, a mode for embodying the present invention (hereinafter,referred to as the embodiment) will be described in the following order:

1. Overall configuration of display apparatus (examples of planarconfiguration, circuit configuration, configuration of protectioncircuit, configuration of test switch circuit)

2. Configuration of light shielding covering portion (examples ofprotection circuit portion and test switch circuit portion)

3. Sectional structure of light shielding covering portion (examples ofconnection pad portion and switch element portion)

4. Planar configuration of light shielding covering portion (examples ofrouting and connection pad portion and another example of lightshielding covering portion)

5. Manufacturing method of display apparatus (example of forming anodeelectrode after formation of opening defining insulating film)

6. Application Examples (examples of electronic device).

1. Overall Configuration of Display Apparatus Planar Configuration

FIG. 1 is a view used to describe a planar configuration of a displayapparatus according to this embodiment. More specifically, the displayapparatus according to this embodiment includes a display region 10provided at substantially the center of a glass substrate 1, protectioncircuits 20 and a test switch circuit (performance test circuit) 30provided on the periphery of the display region 10 on the glasssubstrate 1, and connection pads 40 connected to a power and respectiveconductor lines of cables (for example, flexible cables FC) throughwhich to input various signals from the outside.

A plurality of pixel portions 11 are disposed horizontally andvertically in a matrix fashion within the display region 10. Each pixelportion 11 is provided with a modulation layer (for example, an organicelectroluminescence layer) that modulates light according to a videosignal and is also provided with a plurality of TFTs (Thin FilmTransistors) that drive respective pixels. The TFTs can be, for example,a write transistor for a vide signal and a drive transistor for drivingthe modulation layer in a pixel according to a video signal.

Wires 50 are installed in the display region 10 for the respectivepixels from outside to inside. The wires 50 are provided in alattice-like arrangement so as to correspond to spaces among the pixelsarrayed horizontally and vertically. The wires 50 include scan linesthrough which to input a signal that sequentially selects writetransistors of the pixels row by row, power supply control lines throughwhich to provide the drive transistors of the pixels with a controlsignal of a power supply voltage, signal lines through which to providethe drive transistors of the pixels with a signal for display (videosignal), and power supply feed lines through which to feed a powersupply voltage.

The respective wires 50 are routed to the connection pads 40 provided onthe outer peripheral portion of the glass substrate 1, which is outsidethe display region 10. Of these wires 50, those serving as the scanlines and the power supply control lines are connected to the protectioncircuits 20 in the middle of the lines. Each protection circuit 20includes switch elements provided in the middle of the respective wires50. In the event of application of a high voltage, such as staticelectricity, the protection circuit 20 protects the display region 10 bypreventing charges from flowing through the wires 50 on the side of thedisplay region 10 using the switch elements.

Of the wires 50, one ends of those serving as the signal lines areconnected to the corresponding protection circuit 20 on the outside ofthe display region 10. Also, the other ends of the signal lines areconnected to the test switch circuit 30 on the outside of the displayregion 10. The test switch circuit 30 includes switch elements used tosend a performance test signal to the signal lines when a performancetest is conducted. The wires 50 are routed to the connection pads 40 viathe protection circuits 20 and the test switch circuit 30 configured asabove.

The switch elements provided to the protection circuits 20 and theswitch circuit 30 are covered with a light shielding film in order notonly to prevent a malfunction triggered by unwanted incident light fromthe outside but also to inhibit reflected light of outside light fromentering into the display region 10.

The display apparatus according to this embodiment is configured in sucha manner that the light shielding film that shields the switch elementsfrom light is provided as a light shielding covering portion to coverthe connection pads 40 while electrically conducting with the connectionpads 40. Owing to this configuration, it becomes possible to protect thesurfaces of the connection pads 40 with the light shielding coveringportion, which makes it unnecessary to expose a material of theconnection pads 40 to the surface in the fabrication sequence after thelight shielding covering portion is formed.

In the case of an organic EL display apparatus in which an organicelectroluminescence layer is disposed between the anode electrode andthe cathode electrode as the pixel portion 11, the light shieldingcovering portion and the anode electrodes are made of the same material.Owing to this configuration, the connection pads 40 are covered with thelight shielding covering portion made of the same material as the anodeelectrodes. Accordingly, in the developing step carried out while theanode electrodes are in an exposed state, because the exposed materialon the connection pads 40 and the exposed material of the anodeelectrodes are the same, it becomes possible to prevent the generationof the battery effect. In other words, it becomes possible to preventthe surfaces of the anode electrodes from becoming uneven throughdecomposition because of the battery effect.

Circuit Configuration

FIG. 2 is a view used to describe the circuit configuration of a majorportion of the display apparatus according to this embodiment. Thecircuit configuration shown in FIG. 2 shows a pixel circuit in anorganic EL display apparatus. For ease of description, a circuit havinga 2×3 matrix of the pixel portions 11 at the center is shown. It shouldbe appreciated, however, that many more pixel portions 11 are providedin practice. In addition, although the protection circuit 20 is providedat one ends of the signal lines and the test switch circuit 30 at theother ends, FIG. 2 shows the test switch circuit 30 at the other endsalone.

More specifically, each pixel portion 11 includes at least onetransistor and a capacity. Each pixel portion 11 shown in FIG. 2 isprovided with a write transistor Trw, a drive transistor Trd, aretention capacity C, and an organic electroluminescence layer EL. Inaddition, as the wires 50, signal lines 53 are installed along thecolumn direction between every two adjacent pixel portions 11 and scanlines 51 and power supply control lines 52 are installed along the rowdirections between every two adjacent pixel portions 11.

Each scan line 51 is connected to the gates of the write transistors Trwof a plurality of the pixel portions 11 arrayed along the row direction.Also, each signal line 53 is connected to the drains of the writetransistors Trw of a plurality of the pixel portions 11 arrayed alongthe column direction. The source of each write transistor Trw isconnected to the gate of the corresponding drive transistor Trd. Eachpower supply control line 52 is connected to the drains of the drivetransistors Trd of a plurality of the pixel portions 11 arrayed alongthe row direction. The source of each drive transistor Trd is connectedto the anode electrode of the corresponding organic electroluminescencelayer EL. Also, each retention capacity C is connected between the gateand the source of the corresponding drive transistor Trd. Commonpotential is applied to the cathode electrode of the organicelectroluminescence layer EL in each pixel portion 11.

In this embodiment, the connection pads 40 are provided at the both endsof the scan lines 51 and the power supply control lines 52. Also, theprotection circuits 20 are provided to the scan lines 51 and the powersupply control lines 52 on the outside of the display region 10 in themiddle of the respective lines 51 and 52 all the way up to theconnection pads 40. The connection pads 40 are provided at one ends ofthe signal lines 53 and the test switch circuit 30 is provided at theother ends.

In order to perform a display operation with the circuit configurationas above, a selection signal is applied sequentially to the scan lines51 and a display by the pixel portions 11 in the selected row isperformed sequentially. More specifically, when a selection signal isapplied to a scan line 51, the write transistors Trw of the pixelportions 11 connected to this scan line 51 come ON. A video signalcorresponding to the pixel portions 11 in the selected row is sentsequentially from the signal lines 53 to the respective pixel portions11 so that charges corresponding to the video signal are sent to thecorresponding retention capacities C from the write transistors Trw thatare ON. Further, a voltage corresponding to the video signal is appliedto the gates of the drive transistors Trd. In response to this voltage,a voltage is applied to the anode electrodes of the organicelectroluminescence layers EL from the power supply control lines 52.Accordingly, a voltage corresponding to the video signal is appliedbetween the anodes and the cathodes and organic electroluminescencelight emission is achieved. This operation is performed by the pixelportions 11 connected to the scan lines 51 to which the selection signalis sent sequentially. A video display by the display region 10 is thusachieved.

Configuration of Protection Circuit

FIG. 3 is a pattern layout view used to describe an example of theconfiguration of the protection circuit 20. As is shown in the circuitdiagram in the inset of the drawing, the protection circuit 20 is of aconfiguration in which two switch elements (transistors Tr201 and Tr202)are connected to the wire 50 (the scan line 51 or the power supplycontrol line 52). Of these two transistors, the drain D of thetransistor Tr201 is connected to Vdd and both the gate G and the sourceS are connected to the wire 50. Also, the drain D of the othertransistor Tr202 is connected to the wire 50 and both the gate G and thesource S are connected to Vss.

In the pattern layout, the transistor Tr201 is disposed on one side andthe other transistor Tr202 is disposed on the other side with the wire50 in between at the center. Wires 21 and 22 used to apply Vdd and Vss,respectively, are formed as a first metal layer and disposed so as tocross the wire 50 (the scan line 51 or the power supply control line52). The wire 50 (the scan line 51 or the power supply control line 52)is formed as a second metal layer.

In the pattern layout as above, a light shielding film 60 represented bya frame indicated by a broken line in the drawing is provided on the twotransistors Tr201 and Tr202 formed of TFTs in the related art. Byproviding the light shielding film 60, not only does it become possibleto prevent a malfunction triggered by unwanted light coming incident onthe transistors Tr201 and Tr202 from the outside, but it also becomespossible to inhibit reflected light of outside light from entering intothe display region 10.

Configuration of Test Switch Circuit

FIG. 4 is a pattern layout view used to describe one example of theconfiguration of the test switch circuit 30. As is shown in the circuitdiagram in the inset of the drawing, the test switch circuit 30 is of aconfiguration in which a switch element (transistor Tr301) is connectedto the wire 50 (signal line 53). The source S of the transistor Tr301 isconnected to the wire 50 (signal line 53), the gate G is connected to atest selection line Ntest, and the drain D is connected to a test signalline Vtest.

In the pattern layout, the gate G of the transistor Tr301 is formed as afirst metal layer and the wires 50 (signal lines 53) and wires 31 and 32of the test selection line Ntest and the test signal line Vtest,respectively, are formed as a second metal layer. In order to perform aperformance test of the pixel portions 11, the transistor Tr301 isclosed by applying a predetermined voltage to the test selection lineNtest and then a test signal supplied from the test signal line Vtest issent to the wire 50 (signal line 53). Accordingly, the test signal issent to the circuit forming the pixel portion 11 and an operation testis carried out.

In the pattern layout as above, the light shielding film 60 representedby a frame indicated by a broken line in the drawing is provided on thetransistor Tr301 formed of a TFT in the related art. By providing thelight shielding film 60, not only does it become possible to prevent amalfunction triggered by unwanted light coming incident on thetransistor Tr301 from the outside, but it also becomes possible toinhibit reflected light of outside light from entering into the displayregion 10.

2. Configuration of Light Shielding Covering Portion Protection CircuitPortion

FIG. 5 is a pattern layout view used to describe a light shieldingcovering portion in a protection circuit portion of the displayapparatus according to this embodiment. As has been described above, theprotection circuits 20 having two transistors Tr201 and Tr202 for eachline are provided to the scan lines 51 and the power supply controllines 52. Also, the scan lines 51 and the power supply control lines 52are routed to the connection pads 40 from the display region 10 (notshown) via the protection circuits 20.

In this embodiment, as indicated by a broken line in the drawing, alight shielding covering portion 61 is provided as a light shieldingfilm so as to cover not only every two transistors Tr201 and Tr202 inthe protection circuits 20 but also the corresponding connection pad 40while electrically conducting with the connection pad 40.

By providing the light shielding covering portion 61 in this manner, notonly does it become possible to shield every two transistors Tr201 andTr202 in the protection circuits 20, but it also becomes possible toprevent the potential of the light shielding covering portion 61 fromfloating. Also, by providing the light shielding covering portion 61 onthe connection pad 40, it becomes possible to prevent the material ofthe connection pad 40 from undergoing the fabrication sequence in anexposed state.

Herein, the light shielding covering portion 61 is made of the samematerial in the same layer as the anode electrode, which is one of theelectrodes that apply a voltage to the organic electroluminescence layerof the pixel portion 11. Owing to this configuration, the exposedmaterial (the material of the light shielding covering portion 61)electrically conducting with the connection pad 40 is the same as thematerial of the anode electrode in the developing step carried out whilethe anode electrode is in an exposed state. It is therefore possible toprevent the battery effect from being generated in the developing stepor the like.

Test Switch Circuit Portion

FIG. 6 is a pattern layout view used to describe a light shieldingcovering portion in a test switch circuit portion in the displayapparatus according to this embodiment. As has been described above, thetest switch circuit 30 having the transistors Tr301 is provided to thesignal lines 53.

In this embodiment, as indicated by a broken line in the drawing, alight shielding covering portion 61 is provided as a light shieldingfilm to cover not only the transistors Tr301 of the test switch circuit30 but also the connection pads 40 while electrically conducting withthe connection pads 40.

The connection pads 40 electrically conducting with the light shieldingcovering portion 61 may not be the connection pads 40 electricallyconducting with the wires (the scan lines 51 and the power supplycontrol lines 52) connected to the protection circuits 20 as with thelight shielding covering portions 61 in the protection circuits 20described above. According to the example shown in FIG. 6, theconnection pads 40 electrically conducting with the power supply feedlines 54 in the vicinity of the test switch circuit 30 are connected tothe light shielding covering portion 61.

In the planar configuration of the display apparatus shown in FIG. 1,the power supply feeding flexible cables FC are connected to the rightand left end portions of the glass substrate 1 on which the test switchcircuit 30 is disposed, that is, the upper right and the upper left ofthe glass substrate 1. Accordingly, the connection pads 40 connected tothe conductors of these flexible cables FC are provided at both theupper right and the upper left of the glass substrate 1.

According to the example shown in FIG. 6, the connection pads 40 aredisposed at the upper right and at the upper left of the glass substrate1. The light shielding covering portion 61 is connected to theseconnection pads 40 and also extends onto the transistors Tr301 of thetest switch circuit 30 so as to play a role of a light shield.

As has been described, by providing the light shielding covering portion61, not only does it become possible to shield the transistors Tr301 ofthe test switch circuit 30 from light, but it also becomes possible toprevent the potential of the light shielding covering portion 61 fromfloating. Also, by providing the light shielding covering portion 61 onthe connection pad 40, it becomes possible to prevent the material ofthe connection pad 40 from undergoing the fabrication sequence in anexposed state.

More specifically, as with the case described above, the light shieldingcovering portion 61 is made of the same material in the same layer asthe anode electrode, which is one of the electrodes that apply a voltageto the organic electroluminescence layer of the pixel portion 11. Owingto this configuration, the exposed material (the material of the lightshielding covering portion 61) electrically conducting with theconnection pads 40 is the same as the material of the anode electrodesin the developing step carried out while the anode electrodes are in anexposed state. It thus becomes possible to prevent the battery effectfrom being generated in the developing step or the like.

3. Sectional Structure of Light Shielding Covering Portion ConnectionPad Portion

FIG. 7 is a cross section taken on line A-A′ of FIG. 6. In other words,this drawing shows a cross section at the connection pad portion. Theconnection pads 40 are formed by patterning the first metal layer andthe second metal layer on the glass substrate 1 into a predeterminedshape. One connection pad 40 is isolated from an adjacent connection pad40 by a gate insulating film or a passivation film and openings aredefined by patterning an insulting planarizing film. The light shieldingcovering portion 61 is provided to these openings so as to electricallyconduct with the second metal layer of the connection pads 40.

Titanium (Ti) is used for the second metal layer of the connection pad40. From the viewpoint of preventing hillock or the like, the laminatedstructure of titanium (Ti)-Aluminum (Al)-Titanium (Ti) may be used asthe second metal layer. Meanwhile, the anode electrode that applies avoltage to the organic electroluminescence layer is made of Al alloy.Accordingly, in the fabrication sequence carried out while the secondmetal layer and the anode electrode are in an exposed state, a currentcircuit is formed because of a redox potential difference between Al andTi when the anode electrode and the second metal layer are soaked in anelectrolytic peeling liquid. Hence, a battery corrosion reaction takesplace, which lowers the reflectance on the surface of the anodeelectrode.

Lowering of the reflectance gives rise to deterioration incharacteristic and reliability of the organic electroluminescence layer.The reason why is as follows. That is, when the reflectance of the anodeelectrode is lowered, it becomes necessary to flow a current larger thana normal current to the organic electroluminescence layer in order toobtain the luminance as high as the luminance in a case where thereflectance is not lowered. Accordingly, the organic electroluminescencelayer deteriorates faster than in a normal case. In addition, powerconsumption of the display apparatus increases and so does heatgeneration.

In this embodiment, the light shielding covering portion 61 made of thesame material as the anode electrode is provided on the second metallayer of the connection pads 40. Owing to this configuration, even whensoaked in an electrolytic peeling liquid in the fabrication sequencecarried out while the anode electrodes and the connection pads 40 are inan exposed state, a battery corrosion reaction will not take placebecause the anode electrodes and the second metal layer are made of thesame metal. Hence, the reflectance on the surfaces of the anodeelectrodes is not lowered.

Switch Element Portion

FIG. 8 is a cross section taken on line B-B′ of FIG. 6. In other words,this drawing shows a cross section of the test switch circuit 30 at theportion of the transistor Tr301. The transistor Tr301 is formed of agate electrode (first metal layer) formed on the glass substrate 1, asemiconductor layer (μC-Si: microcrystal silicon) formed on the gateelectrode via a gate insulting film, and a source electrode (secondmetal layer) and a drain electrode (second metal layer) formed on thegate electrode via the semiconductor layer.

An etching stopper is provided on the semiconductor layer interposedbetween the source electrode and the drain electrode. Also, an n+semiconductor layer is provided between both the source electrode andthe drain electrode and the semiconductor layer.

A passivation film is formed on the transistor Tr301 and an insulatingplanarizing film is formed on the passivation film. The surface of theinsulating planarizing film is planarized and the light shieldingcovering portion 61 is formed on the insulating planarizing film. Thelight shielding covering portion 61 is made of the same material as theanode electrodes. Further, the opening defining insulating film isformed on the light shielding covering portion 61.

The sectional structure of the connection pad portion and the transistorportion described above is the same in the other connection pads and theother transistor portion of the protection circuit 20.

4. Planar Configuration of Light Shielding Covering Portion Routing andConnection Pad Portion

FIG. 9 is a view used to describe the planar configuration of the lightshielding covering portion and it shows the routing and the connectionpad portion. More specifically, the light shielding covering portion 61is formed so as to cover on the connection pad 40 while electricallyconducting with the connection pad 40. The light shielding coveringportion 61 is installed above the wire 50 and connected to the wire 50,which is the second metal layer, at the contact portion. By electricallyconducting the wire 50 with the light shielding covering portion 61 inthis manner, it becomes possible to lower the resistance value of thewire 50 in comparison with a case where the light shielding coveringportion 61 is absent.

Another Example of Light Shielding Covering Potion

FIG. 10 is a plan view used to describe another example of the lightshielding covering portion. This drawing shows the light shieldingcovering portion 61 provided on the transistors Tr201 and Tr202 of theprotection circuit 20. It should be appreciated, however, that the lightshielding covering portion 61 provided on the transistors in the testswitch circuit 30 is of the same configuration.

The light shielding covering portion 61 is provided on the transistorsTr201 and Tr202 serving as switching elements and also on the connectionpad 40. Moreover, the light shielding covering portion 61 electricallyconducts with the connection pad 40. According to the example shown inFIG. 10, parts of the light shielding covering portion 61 connecting thepart on the transistors Tr201 and Tr202 to the part on the connectionpad 40 are not placed directly above the wire 50 but at slightlydisplaced positions. By placing the connection parts in this manner, itbecomes possible to reduce a parasitic capacity between the wire 50 andthe light shielding covering portion 61 in comparison with a case wherethe light shielding covering portion 61 is placed directly above thewire 50.

5. Manufacturing Method of Display Apparatus

FIG. 11 through FIG. 14 are schematic cross sections used tosequentially describe the manufacturing method of the display apparatusaccording to this embodiment. Initially, as is shown in FIG. 11,transistors for each pixel are formed on the glass substrate 1.According to the example shown in FIG. 11, a write transistor Trw and adrive transistor Trd are formed on the glass substrate 1. Morespecifically, the gate electrodes G of the both transistors are formedon the glass substrate 1 from the first metal layer and a semiconductorlayer (μC-Si: microcrystal silicon) is formed on the gate electrodes Gvia a gate insulating film. The source electrode S and the drainelectrode D are formed on the semiconductor layer via an n+semiconductor layer, which are covered with a passivation film.

Subsequently, as is shown in FIG. 12, a first insulating film 71 isformed on the passivation film covering the write transistor Trw and thedrive transistor Trd formed on the glass substrate 1. The firstinsulating film 71 can be made of a photosensitive organic material,such as polyimide resin, polybenzoxazole resin, novolac resin, andpolyhydroxystyrene or acrylic resin. The photosensitive organic materialis applied on the passivation film followed by exposure and peeling,after which the glass substrate 1 is baked. The first insulating film 71is consequently made into an insulating planarizing film having aplanarized surface.

Subsequently, a second insulating film 72 is formed on the insulatingplanarizing film, which is the first insulating film 71. By providingthe second insulating film 72 with openings at predetermined positions,the second insulating film 72 is made into an opening defininginsulating film. The second insulating film 72 can be made of aphotosensitive organic material, such as polyimide resin,polybenzoxazole resin, novolac resin, and polyhydroxystyrene or acrylicresin. This material is applied on the insulating planarizing filmfollowed by exposure and peeling. The second insulating film 72 is madeinto an opening defining insulating film by providing openings at thepositions corresponding to the display portions of pixels and subsidiarywires.

Subsequently, as is shown in FIG. 13, an anode electrode 81 and powersupply subsidiary wires 82 are formed in the openings defined by theopening defining insulating film, which is the second insulating film72. More specifically, the anode electrode 81 is formed in the openingthat will be made into the display portion of a pixel and the powersupply subsidiary wires 82 are formed in the openings for the powersupply subsidiary wire provided on the periphery of the anode electrode81. The anode electrode 81 and the power supply subsidiary wires 82 canbe formed into a predetermined pattern by applying resist on a film ofAl alloy deposited, for example, by sputtering followed by exposure,development, etching, and removal of the resist.

When the anode electrode 81 is developed via a resist film, the surfacesof the unillustrated connection pads 40 are covered with the resistfilm. Hence, even when the surfaces of the connection pads 40 are madeof Ti, they are protected so as not to be developed. Hence, no batteryeffect due to a developing liquid is generated and no corrosion occursin the anode electrode 81.

Subsequently, as is shown in FIG. 14, a common layer (hole injectionlayer and a hole transport layer) 91, which is an organicelectroluminescence layer, is formed on the anode electrode 81 and thepower supply subsidiary wires 82. Further, a luminous layer and anelectron transport layer are formed on the common layer 91. The luminouslayer and the electron transport layer are formed as a luminous layerand an electron transport layer, 92 b, corresponding to B (blue), aluminous layer and an electron transport layer, 92 r, corresponding to R(red), and a luminous layer and an electron transport layer, 92 g,corresponding to G (green), at the positions coinciding with therespective corresponding pixels. It should be noted that the order inwhich to form the luminous layers and the electron transport layers, 92b, 92 r, and 92 g, is not particularly limited.

Subsequently, a cathode electrode 83 is formed on the luminous layersand the electron transport layers of respective colors, 92 b, 92 r, and92 g.

According to the manufacturing method as above, after the secondinsulating film 72 defining the openings for the respective pixels isformed, the anode electrode 81 is formed in the opening. It is thereforepossible to prevent influences in the step of forming the secondinsulating film 72 from being given to the anode electrode 81.Consequently, the reflectance on the surface of the anode electrode 81will not be lowered. Because the reflectance on the surface of the anodeelectrode 81 will not be lowered, it is not necessary to increase acurrent for unnecessarily increasing the luminance. Deterioration of theorganic electroluminescence layer can be thus suppressed. In addition,it becomes possible to suppress an increase of power consumption and anincrease of heat generation of the display apparatus.

Another example of the manufacturing method of the display apparatusaccording to this embodiment is shown in FIG. 15 through FIG. 17.Initially, as is shown in FIG. 15, transistors for each pixel are formedon the glass substrate 1. According to the example shown in FIG. 15, awrite transistor Trw and a drive transistor Trd are formed on the glasssubstrate 1. More specifically, gate electrodes G of the bothtransistors are formed on the glass substrate 1 from the first metallayer and a semiconductor layer (μC-Si: microcrystal silicon) is formedon the gate electrodes G via a gate insulating film. Then, a sourceelectrode S and a drain electrode D are formed on the semiconductorlayer via an n+ semiconductor layer, which are covered with thepassivation film.

Subsequently, a first insulating film 71 is formed on the passivationfilm covering the write transistor Trw and the drive transistor Trdformed on the glass substrate 1. The first insulating film 71 can bemade of a photosensitive organic material, such as polyimide resin,polybenzoxazole resin, novolac resin, and polyhydroxystyrene or acrylicresin. The photosensitive organic material is applied on the passivationfilm followed by exposure and peeling, after which the glass substrate 1is baked. The first insulating film 71 is thus made into an insulatingplanarizing film having a planarized surface.

Subsequently, an anode electrode 81 and power supply subsidiary wires 82are formed on the insulating planarizing film, which is the firstinsulating film 71. The anode electrode 81 and the power supplysubsidiary wires 82 can be formed into a predetermined pattern byapplying resist on a film of Al alloy deposited, for example, bysputtering followed by exposure, development, etching, and removal ofthe resist.

Herein, when the anode electrode 81 and the power supply subsidiarywires 82 are formed, the same material is also provided on the surfacesof the unillustrated connection pad portion. When configured in thismanner, the surfaces of the connection pads 40 are made of the samemetal as the anode electrode 81 and the power supply subsidiary wires82. Hence, no battery effect due to a developing liquid will begenerated and no corrosion occurs in the anode electrode 81.

Subsequently, as is shown in FIG. 16, a second insulating film 72 isformed on the anode electrode 81 and the power supply subsidiary wires82. By providing the second insulating film 72 with openings at thepredetermined positions, the second insulating film 72 is made into theopening defining insulating film. The second insulating film 72 can bemade of a photosensitive organic material, such as polyimide resin,polybenzoxazole resin, novolac resin, and polyhydroxystyrene or acrylicresin. This material is applied on the insulating planarizing filmfollowed by exposure and peeling. The second insulating film 72 is thenmade into the opening defining insulating film by providing openings atpositions corresponding to the display portions of pixels and subsidiarywires.

Subsequently, as is shown in FIG. 17, a common layer (hole injectionlayer and a hole transport layer) 91, which is an organicelectroluminescence layer, is formed on the anode electrode 81 and thesecond insulating film 72 made into the opening defining insulatingfilm. Further, a luminous layer and an electron transport layer areformed on the common layer 91. The luminous layer and the electrontransport layer are formed as a luminous layer and an electron transportlayer, 92 b, corresponding to B (blue), a luminous layer and an electrontransport layer, 92 r, corresponding to R (red), and a luminous layerand an electron transport layer, 92 g, corresponding to G (green), atthe positions coinciding with the respective corresponding pixels. Itshould be noted that the order in which to form the luminous layers andthe electron transport layers, 92 b, 92 r, and 92 g, is not particularlylimited.

Subsequently, a cathode electrode 83 is formed on the luminous layersand the electron transport layers of respective colors, 92 b, 92 r, and92 g.

According to this manufacturing method, as with the manufacturing methoddescribed first as above, it is possible to prevent the occurrence ofcorrosion on the surface of the anode electrode 81 during thedevelopment. Consequently, the reflectance on the surface of the anodeelectrode 81 will not be lowered. Because the reflectance on the surfaceof the anode electrode 81 will not be lowered, it is not necessary toincrease a current for unnecessarily increasing the luminance.Deterioration of the organic electroluminescence can be thus suppressed.In addition, it becomes possible to suppress an increase of powerconsumption and an increase of heat generation of the display apparatus.

6. Application Examples Electronic Device

Examples when the display apparatus according to this embodiment isapplied to electronic devices will now be described.

As is shown in FIG. 18, the display apparatus according to thisembodiment includes a display apparatus of a flat modular shape. Forexample, a display module is formed by providing a pixel array portion2002 a in which a luminous region and pixels formed of thin filmtransistors or the like are formed integrally in a matrix fashion on aninsulating substrate 2002, placing an adhesive agent 2021 so as tosurround the pixel array portion (pixel matrix portion) 2002 a, andlaminating a counter substrate 2006 made of glass. When the necessityarises, a color filter, a protection film, and a light shielding film,or the like may be provided to the transparent counter substrate 2006.The display module may be provided, for example, with an FPC (FlexiblePrinted Circuit) 2023 as a connecter to input a signal into the pixelarray portion 2002 a from the outside and to output a signal from thepixel array portion 2002 a to the outside.

The display apparatus according to this embodiment described above isapplicable to various electronic devices shown in FIG. 19 through FIG.23G, for example, a display apparatus of an electronic device in anyfield that displays a video signal inputted into the electronic deviceor a video signal generated in the electronic device as an image or avideo, more specifically, a digital camera, a notebook personalcomputer, a mobile terminal device, such as a mobile phone, and a videocamera. In the following, an example of an electronic device to whichthis embodiment is applied will be described.

FIG. 19 is a perspective view of a TV set to which this embodiment isapplied. The TV set as an application example includes a video displayscreen portion 101 formed of a front panel 102 and a filter glass 103and employs the display apparatus of this embodiment as the videodisplay screen portion 101.

FIG. 20A and FIG. 20B are perspective views of a digital camera to whichthis embodiment is applied. FIG. 20A is a perspective view when viewedfrom the front and FIG. 20B is a perspective view when viewed from therear. The digital camera as an application example includes a luminousportion 111 for flashlight, a display portion 112, a menu switch 113, ashutter button 114, and so forth and employs the display apparatusaccording to this embodiment as the display portion 112.

FIG. 21 is a perspective view showing a notebook personal computer towhich this embodiment is applied. The notebook personal computer as anapplication example includes a main body 121 provided with a keyboard122 operated when characters and the like are inputted, a displayportion 123 on which to display an image, and so forth and employs thedisplay apparatus of this embodiment as the display portion 123.

FIG. 22 is a perspective view showing a video camera to which thisembodiment is applied. The video camera as an application exampleincludes a main body portion 131, a subject imaging lens 132 provided onthe side surface facing frontward, an imaging start and stop switch 133,a display portion 134, and so forth and employs the display apparatusaccording to this embodiment as the display portion 134.

FIG. 23A through FIG. 23G are views showing a mobile terminal device,for example, a mobile phone, to which this embodiment is applied. FIG.23A is a front view of the mobile phone in an opened state and FIG. 23Bis aside view in an opened state. FIG. 23C is a front view of the mobilephone in a closed state. FIG. 23D is a left side view, FIG. 24E is aright side view, FIG. 23F is a top view, and FIG. 23G is a bottom viewin a closed state. The mobile phone as an application example includesan upper casing 141, a lower casing 142, a link portion (herein, a hingeportion) 143, a display 144, a sub-display 145, a picture light 146, acamera 147, and so forth and employs the display apparatus according tothis embodiment as the display 144 and the sub-display 145.

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2009-028050 filedin the Japan Patent Office on Feb. 10, 2009, the entire contents ofwhich is hereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

What is claimed is:
 1. A method of forming a display apparatus having a display region including at least one pixel, the method comprising: (a) forming switch elements on a substrate; (b) covering the switching elements with a planarizing layer; (c) providing a connection pad outside of the display region; (d) providing an anode electrode and wires between the planarizing layer and an insulating layer with the anode electrode and the wires on the planarizing layer and with the insulating layer having a first opening exposing the anode electrode and second openings exposing the wires, the anode, (e) covering the anode electrode, the wires, and the connection pad with a same material; and (f) forming on the anode electrode, in this order, an organic electroluminescence layer and a cathode electrode.
 2. The method of claim 1, wherein step (d) comprises first forming on the planarizing layer the insulating layer with the first opening and the second openings and then forming the anode electrode in the first opening and the wires in the second openings.
 3. The method of claim 1, wherein step (d) comprises first forming the anode electrodes and the wires on the planarizing layer and then forming the insulating layer with the first opening and the second openings.
 4. The method of claim 1, wherein the switch elements are read and write transistors.
 3. A method of forming a display apparatus having a display region with at least one pixel, the method comprising: forming transistors on a substrate; forming a passivation film over the transistors; forming a first insulating layer over the passivation film, the first insulating also being effective as a planarizing layer; forming a second insulating layer over the first insulating layer with a first opening and second openings at predetermined positions; providing a connection pad outside of the display region; forming an anode electrode within the first opening and power supply subsidiary wires within the second openings with a same material over the anode electrode and the connection pad; forming an organic electroluminescence layer on the anode electrode and the power supply subsidiary wires; forming aluminous layer and an electron transport layer on the organic electroluminescence layer at a position corresponding to the anode electrode; and forming a cathode electrode at the position of the anode electrode.
 4. The method of claim 3, wherein the substrate is made of a glass.
 5. The method of claim 3, wherein the first insulating film is made of a photosensitive organic material.
 6. The method of claim 5, wherein the first insulating layer is subject to exposure and peeling, and then the substrate is baked.
 7. The method of claim 3, wherein the second insulating film is made of a photosensitive organic material.
 8. The method of claim 3, wherein the same material covering the anode electrode and the connection pads is a photoresist material.
 9. A method of forming a display apparatus having a display region with at least one pixel, the method comprising: forming transistors on a substrate; forming a passivation film over the transistors; forming a first insulating layer over the passivation film, the first insulating also being effective as a planarizing layer; providing a connection pad outside of the display region; forming an anode electrode and power subsidiary wires on the first insulting layer with a same material over the anode electrode and the connection pad; forming a second insulating layer over the first insulating layer with a first opening exposing the anode electrode and second openings exposing the power subsidiary wires; forming an organic electroluminescence layer on the anode electrode and the power supply subsidiary wires; forming a luminous layer and an electron transport layer on the organic electroluminescence layer at a position corresponding to the anode electrode; and forming a cathode electrode at the position corresponding to the anode electrode.
 10. The method of claim 9, wherein the substrate is made of a glass.
 11. The method of claim 9, wherein the first insulating film is made of a photosensitive organic material.
 12. The method of claim 11, wherein the first insulating layer is subject to exposure and peeling, and then the substrate is baked.
 12. The method of claim 9, wherein the second insulating film is made of a photosensitive organic material.
 13. The method of claim 3, wherein the same material covering the anode electrode and the connection pad is a photoresist material. 